WASHINGTON — President Obama nominated Massachusetts Senator John Forbes Kerry as the next secretary of state Friday, turning to the chairman of the Senate Foreign Relations Committee and one of his earliest political allies to guide American diplomacy in an “uncertain world” during the next four years.

The selection of the 69-year-old Kerry, which came after UN Ambassador Susan Rice withdrew her name from consideration last week, was heralded across the political divide as a wise choice of a fully tested player on the international stage who can dive into some of the world’s most challenging problems — from the civil war in Syria and fears of an Iranian nuclear bomb to winding down the war in Afghanistan and navigating America’s complex economic and security relations with a rising China.

If Kerry is confirmed, as expected, Massachusetts Governor Deval Patrick would name a temporary replacement to fill his seat and a special election would be held later next year to complete his term, which is up in 2014.

The nomination to replace Hillary Clinton is the capstone of a three-decade political career that began when Kerry, the son of a Foreign Service officer, returned from the Vietnam War a decorated veteran to become a leading voice of the antiwar movement.

“In a sense, John’s entire life has prepared him for this role,” Obama said during a joint appearance with Kerry, his wife, Teresa Heinz Kerry, and Vice President Joe Biden in the Roosevelt Room — just steps from the Oval Office that Kerry tried to attain as the Democrats’ nominee for president in 2004. “Having served with valor in Vietnam, he understands that we have a responsibility to use American power wisely, especially our military power.”

The president also referenced Kerry’s experience on the Foreign Relations Committee, adding that “few individuals know as many presidents and prime ministers, or grasp our foreign policies as firmly as John Kerry.’’

The committee will conduct Kerry’s confirmation hearings, which are expected to be held next month when the new Congress returns. New Jersey Senator Robert Menendez will oversee the hearings, which are expected to be quick and relatively smooth.

Several Republican senators such as Bob Corker of Tennessee, a member of the Foreign Relations Committee, indicated they would support the nomination.

Still, Kerry will probably face a few tough questions on a range of thorny issues, said Senator Chuck Grassley, a Republican from Iowa who served with Kerry on the Senate Select Committee on POW/MIA Affairs two decades ago.

One is likely to be Syria. Kerry has been criticized for fostering a relationship with President Bashar Assad before the civil war there. In Assad, Kerry initially saw a potentially transformative figure in the Middle East and he had visited with him several times after he assumed the presidency from his father, Hafez, a notorious despot.

Instead, Bashar Assad’s brutal crackdown on political opponents has stunned Western officials.

Republican Senator John McCain called on his friend Kerry on Friday to take a stronger stance against Syria, including supporting a no-fly zone to protect anti-Assad forces.

“I think Senator Kerry was good on Libya and I am very disappointed he has not taken a more vigorous position on Syria,” McCain told reporters. The Arizona Republican had previously said he would likely support Kerry in such a nomination.

Other observers in GOP foreign policy circles expressed reservations about the choice.

“I’m hopeful about him. But he has to cut the politics,” said Richard Grennell, who has worked for the last four Republican ambassadors to the United Nations.

Mixing politics with foreign policy, Grennell said, can be a dangerous game.

“To run the State Department you have to be nonpartisan,” Grennell added. “It is an incredibly important post. I am hopeful he will enter the State Department and immediately take off his Democratic Party hat.”

But other members of the GOP foreign policy establishment embraced the president’s choice.

“I am very high on John Kerry,” said retired three-star general Brent Scowcroft, who served as national security adviser for Presidents George H.W. Bush and Gerald Ford and remains a leading voice. “He is not beset by illusions or campaigns on behalf of abstract principles. His instincts are solid. I think he’ll do a great job.”

Senator Olympia Snowe of Maine, a Republican who is retiring next month, said she expects Kerry’s nomination to sail through the Senate.

Even if some of her Republican colleagues disagree with Kerry on certain foreign policy matters, “there is widespread acknowledgment that with his experience and common sense in the realm of American foreign policy, he will be easily confirmed,” she said in an interview.

Foreign leaders “trust him and he is a voice of reason,” Snowe said. “He comes with a credibility that will be essential for the president and the country.”

Kerry would be replacing Clinton, who is stepping down after winning praise for being one of the nation’s most-engaged secretaries of state. Clinton, who has visited more nations during her tenure than any of her predecessors, was not at the announcement Friday. She is still recovering from a concussion suffered in a fall.

Kerry will have to wait to learn the other members of Obama’s second-term Cabinet. Administration officials said they had hoped to group Kerry’s announcement with other nominees, but Obama has not yet settled on someone to replace David Petraeus as head of the CIA and outgoing Secretary of Defense Leon Panetta. One potential Pentagon pick, former Republican senator Chuck Hagel of Nebraska, has been criticized for what some say is his weak support for Israel.

In naming Kerry to the post, the president also spoke of their strong political alliance in recent years.

He noted that it was Kerry who invited him, as an Illinois state senator, to address the 2004 Democratic National Convention in Boston. That speech catapulted Obama to national prominence.

Obama generated a few chuckles when he brought up some of their most recent encounters, such as when Kerry played the role of Mitt Romney in debate preparations during Obama’s reelection campaign against the former Massachusetts governor.

“Of course nothing brings two people closer together than weeks of debate prep,” Obama said, turning to Kerry. “John, I’m looking forward to working with you instead of debating you.”

If confirmed by the Senate, Kerry would join a line of US statesmen, beginning with
Thomas Jefferson as the nation’s first secretary of state. He will face an international scene as complicated as ever.

“I think it’s fair to say that there are going to be some great challenges ahead,” Obama said.

But Obama also expressed confidence in Kerry’s readiness:

“He is not going to need a lot of on-the-job training.”

Bender can be reached at bender@globe.com. Follow him on Twitter @GlobeBender. Tracy Jan and Bobby Caina Calvan of the Globe staff contributed to this report.